Calpains mediate isoproterenol-induced hypertrophy through modulation of GRK2 (original) (raw)
Related papers
Calpain inhibition preserves myocardial structure and function following myocardial infarction
AJP: Heart and Circulatory Physiology, 2009
Mani SK, Balasubramanian S, Zavadzkas JA, Jeffords LB, Rivers WT, Zile MR, Mukherjee R, Spinale FG, Kuppuswamy D. Calpain inhibition preserves myocardial structure and function following myocardial infarction. Cardiac pathology, such as myocardial infarction (MI), activates intracellular proteases that often trigger programmed cell death and contribute to maladaptive changes in myocardial structure and function. To test whether inhibition of calpain, a Ca 2ϩ -dependent cysteine protease, would prevent these changes, we used a mouse MI model. Calpeptin, an aldehydic inhibitor of calpain, was intravenously administered at 0.5 mg/kg body wt before MI induction and then at the same dose subcutaneously once per day. Both calpeptin-treated (n ϭ 6) and untreated (n ϭ 6) MI mice were used to study changes in myocardial structure and function after 4 days of MI, where end-diastolic volume (EDV) and left ventricular ejection fraction (EF) were measured by echocardiography. Calpain activation and programmed cell death were measured by immunohistochemistry, Western blotting, and TdT-mediated dUTP nick-end labeling (TUNEL). In MI mice, calpeptin treatment resulted in a significant improvement in EF [EF decreased from 67 Ϯ 2% pre-MI to 30 Ϯ 4% with MI only vs. 41 Ϯ 2% with MI ϩ calpeptin] and attenuated the increase in EDV [EDV increased from 42 Ϯ 2 l pre-MI to 73 Ϯ 4 l with MI only vs. 55 Ϯ 4 l with MI ϩ calpeptin]. Furthermore, calpeptin treatment resulted in marked reduction in calpain-and caspase-3-associated changes and TUNEL staining. These studies indicate that calpain contributes to MI-induced alterations in myocardial structure and function and that it could be a potential therapeutic target in treating MI patients. cardiomyocytes; cell death * S. K. Mani and S. Balasubramanian contributed equally to this work.
British Journal of Pharmacology, 2002
The calpains have been proposed to be activated following cardiac ischaemia and to contribute to myocyte damage after myocardial infarction (MI). In this study, the activity of calpains I and II in the infarcted and non-infarcted rat myocardium and the action of the selective calpain inhibitor, CAL 9961, has been investigated.MI was induced by permanent ligation of the left coronary artery. One, 3, 7 and 14 days post MI, the enzymes calpain I and II were separated from homogenates of the interventricular septum (IS) and left ventricular free wall (LVFW) by chromatography on DEAE-Sepharose. The activity of the calpains was measured in sham-operated and MI animals chronically treated with placebo or CAL 9961 (15 mg kg−1 d−1 s.c.) in a synthetic substrate assay. Treatment was started 3 days before MI induction.Calpain I activity reached highest values in IS 14 days post MI, whereas maximum activity of calpain II was measured in LVFW 3 days post MI. In experiments in vitro, CAL 9961 completely inhibited both calpains. In vivo, chronic treatment of MI animals with CAL 9961 partially prevented the increase in calpain I activity in IS and reduced calpain II activity in LVFW to sham levels.Our findings demonstrate that calpains I and II are activated after MI, however, both enzymes differ in their regional and temporal activation within the infarcted myocardium. Chronic inhibition of these enzymes with CAL 9961 might limit the calpain-induced myocardial damage and preserve cardiac structural integrity post MI.The calpains have been proposed to be activated following cardiac ischaemia and to contribute to myocyte damage after myocardial infarction (MI). In this study, the activity of calpains I and II in the infarcted and non-infarcted rat myocardium and the action of the selective calpain inhibitor, CAL 9961, has been investigated.MI was induced by permanent ligation of the left coronary artery. One, 3, 7 and 14 days post MI, the enzymes calpain I and II were separated from homogenates of the interventricular septum (IS) and left ventricular free wall (LVFW) by chromatography on DEAE-Sepharose. The activity of the calpains was measured in sham-operated and MI animals chronically treated with placebo or CAL 9961 (15 mg kg−1 d−1 s.c.) in a synthetic substrate assay. Treatment was started 3 days before MI induction.Calpain I activity reached highest values in IS 14 days post MI, whereas maximum activity of calpain II was measured in LVFW 3 days post MI. In experiments in vitro, CAL 9961 completely inhibited both calpains. In vivo, chronic treatment of MI animals with CAL 9961 partially prevented the increase in calpain I activity in IS and reduced calpain II activity in LVFW to sham levels.Our findings demonstrate that calpains I and II are activated after MI, however, both enzymes differ in their regional and temporal activation within the infarcted myocardium. Chronic inhibition of these enzymes with CAL 9961 might limit the calpain-induced myocardial damage and preserve cardiac structural integrity post MI.British Journal of Pharmacology (2002) 135, 1951–1958; doi:10.1038/sj.bjp.0704661
Tear Me Down: Role of Calpain in the Development of Cardiac Ventricular Hypertrophy
Circulation Research, 2011
Cardiac hypertrophy develops most commonly in response to hypertension and is an independent risk factor for the development of heart failure. The mechanisms by which cardiac hypertrophy may be reversed to reduce this risk have not been fully determined to the point where mechanismspecific therapies have been developed. Recently, proteases in the calpain family have been implicated in regulating the development of cardiac hypertrophy in preclinical animal models. In this review, we summarize the molecular mechanisms by which calpain inhibition has been shown to modulate the development of cardiac (specifically ventricular) hypertrophy. The context within which calpain inhibition might be developed for therapeutic intervention of cardiac hypertrophy is then discussed.
Basic Research in Cardiology, 2003
The onset of heart failure is associated with characteristic changes in myocardial expression of G protein receptor kinase 2 (GRK2). Although, GRK2 significantly contributes to the regulation of myocardial function in the failing heart, the GRK2 expression during cardiac hypertrophy without heart failure remains to be explored. We here report a differential expression of GRK2 in cardiac hypertrophy with or without heart failure in response to a myocardial infarction in the rat. Postmyocardial infarction animals were divided into two groups depending on the absence or presence of pulmonary edema, which is a manifestation of heart failure. Remarkably, cardiac GRK2 expression and activity were inhibited in animals with cardiac hypertrophy without heart failure, whereas animals with heart failure had elevated GRK2. Thus, three weeks after the infarction cardiac GRK2 expression in animals with hypertrophy alone was decreased to 0.34 of control, whereas in the group of animals with heart failure GRK2 expression was 1.89-fold higher than in sham-operated animals. GRK2 activity was affected in a similar way, three and nine weeks after the infarction cardiac GRK2 activity was reduced to 0.58 and 0.62 in animals with hypertrophy without heart failure when compared to sham operated animals. By contrast, GRK2 activity was increased by 1.32and 1.21-fold three and nine weeks postinfarction in animals with heart failure when compared to sham animals. These data suggest that GRK2 expression is differentially regulated in hypertrophic, non-failing and hypertrophic, failing hearts.
Diabetes, 2011
OBJECTIVE-Recently we have shown that calpain-1 activation contributes to cardiomyocyte apoptosis induced by hyperglycemia. This study was undertaken to investigate whether targeted disruption of calpain would reduce myocardial hypertrophy and fibrosis in mouse models of type 1 diabetes. RESEARCH DESIGN AND METHODS-Diabetes in mice was induced by injection of streptozotocin (STZ), and OVE26 mice were also used as a type 1 diabetic model. The function of calpain was genetically manipulated by cardiomyocyte-specific knockout Capn4 in mice and the use of calpastatin transgenic mice. Myocardial hypertrophy and fibrosis were investigated 2 and 5 months after STZ injection or in OVE26 diabetic mice at the age of 5 months. Cultured isolated adult mouse cardiac fibroblast cells were also investigated under high glucose conditions.
Integrating GRK2 and NFkappaB in the Pathophysiology of Cardiac Hypertrophy
G protein coupled receptor kinase type 2 (GRK2) plays an important role in the development and maintenance of cardiac hypertrophy and heart failure even if its exact role is still unknown. In this study, we assessed the effect of GRK2 on the regulation of cardiac hypertrophy. In H9C2 cells, GRK2 overexpression increased atrial natriuretic factor (ANF) activity and enhanced phenylephrine-induced ANF response, and this is associated with an increase of NFκB transcriptional activity. The kinase dead mutant and a synthetic inhibitor of GRK2 activity exerted the opposite effect, suggesting that GRK2 regulates hypertrophy through upregulation of NFκB activity in a phosphorylation-dependent manner. In two different in vivo models of left ventricle hypertrophy (LVH), the selective inhibition of GRK2 activity prevented hypertrophy and reduced NFκB transcription activity. Our results suggest a previously undisclosed role for GRK2 in the regulation of hypertrophic responses and propose GRK2 as potential therapeutic target for limiting LVH.
A calcium stimulated cysteine protease involved in isoproterenol induced cardiac hypertrophy
The Cellular Basis of Cardiovascular Function in Health and Disease, 1997
The purpose of this study was to test the relationship between biochemical and functional changes accompanying β-agonist induced cardiac hypertrophy and the activation of a calcium stimulated cysteine protease. Because the ultrastructural and ionic changes accompanying β-agonist induced cardiac hypertrophy are reminiscent of the actions of the calcium activated neutral protease, calpain, it was hypothesized that lowering calpain activity (by the use of an exogenous inhibitor(s)) would reduce th e extent of hypertrophy. Rats (275-300 g) were randomly assigned to either a control, β-agonist (iso) or cysteine protease inhibitor (E64c) group. Isoproterenol administration (1 mg/kg) resulted in changes for ventricular weight to body weight ratio (↑19%), ventricular [RNA] (↑105.6%), rate of pressure development (↑22% for +dP/dt) and maximum developed left ventricular pressure (↑19%) (p < 0.05) after 3 days. Calpain-like activity (assessed by microplate method) increased by 45% (p < 0.05), while [cAMP] returned to control levels (following a transient rise at 1 day; 606.03 ± 124.1 pmol/g/wet/wt to 937.9 ± 225 (p < 0.05)). E64c (administered 1 h prior to iso) reduced the extent of hypertrophy, from 19 to 12%, and prevented the increases in; total [RNA], left ventricular function, the initial [cAMP] increase and calpain-like activity. It is concluded that a calcium stimulated cysteine protease(s), such as calpain, may be involved in the biochemical and functional changes associated with isoproterenol induced cardiac hypertrophy.
Degradation of GRK2 and AKT is an early and detrimental event in myocardial ischemia/reperfusion
EBioMedicine, 2019
Background: Identification of signaling pathways altered at early stages after cardiac ischemia/reperfusion (I/R) is crucial to develop timely therapies aimed at reducing I/R injury. The expression of G proteincoupled receptor kinase 2 (GRK2), a key signaling hub, is up-regulated in the long-term in patients and in experimental models of heart failure. However, whether GRK2 levels change at early time points following myocardial I/R and its functional impact during this period remain to be established. Methods: We have investigated the temporal changes of GRK2 expression and their potential relationships with the cardioprotective AKT pathway in isolated rat hearts and porcine preclinical models of I/R. Findings: Contrary to the maladaptive up-regulation of GRK2 reported at later times after myocardial infarction, successive GRK2 phosphorylation at specific sites during ischemia and early reperfusion elicits GRK2 degradation by the proteasome and calpains, respectively, thus keeping GRK2 levels low during early I/R in rat hearts. Concurrently, I/R promotes decay of the prolyl-isomerase Pin1, a positive regulator of AKT stability, and a marked loss of total AKT protein, resulting in an overall decreased activity of this pro-survival pathway. A similar pattern of concomitant down-modulation of GRK2/AKT/Pin1 protein levels in early I/R was observed in pig hearts. Calpain and proteasome inhibition prevents GRK2/Pin1/AKT degradation, restores bulk AKT pathway activity and attenuates myocardial I/R injury in isolated rat hearts. Interpretation: Preventing transient degradation of GRK2 and AKT during early I/R might improve the potential of endogenous cardioprotection mechanisms and of conditioning strategies.
British Journal of Pharmacology, 2010
To determine whether KMUP-1, a novel xanthine-based derivative, attenuates isoprenaline (ISO)-induced cardiac hypertrophy in rats, and if so, whether the anti-hypertrophic effect is mediated by the nitric oxide (NO) pathway. Experimental approach: In vivo, cardiac hypertrophy was induced by injection of ISO (5 mg·kg -1 ·day -1 , s.c.) for 10 days in Wistar rats. In the treatment group, KMUP-1 was administered 1 h before ISO. After 10 days, effects of KMUP-1 on survival, cardiac hypertrophy and fibrosis, the NO/guanosine 3′5′-cyclic monophosphate (cGMP)/protein kinase G (PKG) and hypertrophy signalling pathways [calcineurin A and extracellular signal-regulated kinase (ERK)1/2] were examined. To investigate the role of nitric oxide synthase (NOS) in the effects of KMUP-1, a NOS inhibitor, N w -nitro-L-arginine (L-NNA) was co-administered with KMUP-1. In vitro, anti-hypertrophic effects of KMUP-1 were studied in ISO-induced hypertrophic neonatal rat cardiomyocytes. Key results: In vivo, KMUP-1 pretreatment attenuated the cardiac hypertrophy and fibrosis and improved the survival of ISO-treated rats. Plasma NOx (nitrite and nitrate) and cardiac endothelial NOS, cGMP and PKG were all increased by KMUP-1. The activation of hypertrophic signalling by calcineurin A and ERK1/2 in ISO-treated rats was also attenuated by KMUP-1. All these effects of KMUP-1 were inhibited by simultaneous administration of L-NNA. Similarly, in vitro, KMUP-1 attenuated hypertrophic responses and signalling induced by ISO in neonatal rat cardiomyocytes. Conclusions and implications: KMUP-1 attenuates the cardiac hypertrophy in rats induced by administration of ISO. These effects are mediated, at least in part, by NOS activation. This novel agent, which targets the NO/cGMP pathway, has a potential role in the prevention of cardiac hypertrophy.